PARIS - A French court on Thursday confirmed that water and waste management firm Veolia would have to consult unions on its purchase of a 29.9% stake in rival Suez, adding a layer of complexity to the deal.

Veolia said in a statement the ruling was unlikely to delay its plan to take full control of Suez.

Veolia bought gas utility Engie's 29.9% stake Suez in October, as a prelude to launching a takeover offer, but it has come up against various hurdles, including vehement opposition from Suez managers and unions.

A French court ruled last month that unions had to be consulted on Veolia's plan to buy Suez.

Under French law, labour representatives must be consulted about major changes such as a corporate takeover.

Lawyers close to the matter have said unions do not have the power to reverse the deal, but can have it suspended if worker rights have not been respected.

The process would likely take until Feb. 5, Veolia said.

(Reporting by Benjamin Mallet; Writing by Matthieu Protard; Editing by Edmund Blair) ((matthieu.protard@thomsonreuters.com; +33-1-49495381;))